I played around with Bear
http://www.bear-writer.com/ and found it quite interesting. Supports Markdown and has a powerful url scheme (see FAQ on their webpage).
Example:
Create note with quote and add tags:
bear://x-callback-url/create?title={author}:%20{title}&text=Kapitel:%20/{chapter}/%0A*%C2%AB{text}%C2%BB*&tags=Zitate,B%C3%BCcher,Le sen&x-success=marvin3:
Append additional quotes to the same note:
bear://x-callback-url/add-text?title={author}:%20{title}&text=---%0A%0AKapitel:%20/{chapter}/%0A*%C2%AB{text}%C2%BB*&mode=append&x-success=marvin3: